1. Field of the Invention
The present invention relates to a display device and a method of fabricating a display device, and more particularly, to a liquid crystal display panel device and a method of fabricating a liquid crystal display panel device.
2. Description of the Related Art
In general, liquid crystal display (LCD) devices supply an electric field to a liquid crystal material in response to video signals in order to control an arrangement state of liquid crystal molecules of the liquid crystal material, thereby controlling light transmittance in accordance with the video signal to display an image (i.e., a picture).
FIG. 1 is a perspective view of a spacer pattern of a liquid crystal display panel device according to the related art, and FIG. 2 is a diagram of a rubbing direction of upper and lower alignment films of the liquid crystal display panel device of FIG. 1 according to the related art. In FIGS. 1 and 2, a liquid crystal display panel device includes an upper substrate 2 and a lower substrate 6 formed with patterned spacers 10 therebetween. On the upper substrate 2, there are formed a black matrix (not shown), a color filter (not shown), a common electrode (not shown) and an upper alignment film 4 to cover the patterned spacers 10. On the lower substrate 6, there are formed gate lines (not shown), data lines (not shown) crossing and insulated from the gate lines, thin film transistors (not shown) at intersection areas of the gate lines and the data lines, pixel electrodes (not shown) connected to the thin film transistors, and a lower alignment film 8 to cover the pixel electrodes. The upper and lower substrates 6 are joined together using a sealant to form the liquid crystal display panel device.
The pattern spacers 10 maintain a uniform cell gap between the upper and lower substrates 2 and 6, and are formed as a plurality of stripes along a direction parallel to a rubbing direction of the upper and lower substrates 2 and 6.
FIG. 3 is a plan view of the pattern spacer of FIG. 1 according to the related art, and FIG. 4 is another plan view of the pattern spacer of FIG. 1 according to the related art. In FIGS. 3 and 4, the patterned spacers 10 are formed within at least one of a non-display area of the upper substrate 2, or within a non-display area of the lower substrate 6. For example, the patterned spacers 10 may be formed on the upper substrate 2 to overlap a black matrix 14 that is formed to partition color filters 12 of red R, green G, and blue B, or the patterned spacers 10 may be formed on the lower substrate 6 to overlap at least one of the gate line, the data line, and the thin film transistor.
FIGS. 5A to 5D are cross sectional views of a fabrication method of the liquid crystal display panel device of FIG. 1 according to the related art. In FIG. 5A, patterned spacers 10 are formed on an upper substrate 2. Although not shown, the upper substrate 2 has a color filter array that includes a black matrix, color filters, and common electrodes. A lower substrate 6 is provided to face an upper substrate 2, and includes a thin film transistor array having thin film transistors and pixel electrodes.
In FIG. 5B, an alignment material of polyamic acid state is coated on the lower substrate 6 and the upper substrate 2 where the patterned spacers 10 are formed to form an upper alignment film 4 and a lower alignment film 8. Then, the upper and lower substrates 2 and 6, each respectively having the upper and lower alignment films 4 and 8, are fired at about 150° C.
In FIG. 5C, after the firing process and subsequent to completing a rubbing process, a sealant 16 is formed on at least one of the upper and lower substrates 2 and 6.
In FIG. 5D, the upper substrate 2 and the lower substrate 6 are aligned, bonded together, and then the sealant is hardened at about 200˜250° C.
During the hardening process, a chemical hardening reaction, in FIG. 6, is completed to convert the sealant from a polyamic acid to polyimide. Accordingly, the upper and lower alignment films 4 and 8 react with each other at contact areas of the patterned spacers 10, thus the upper and lower alignment films 4 and 8 of the upper and lower substrates 2 and 6 adhere to each other. However, portions of the upper and lower alignment films 4 and 8 stabilize at overlapping areas of the patterned spacers 10, but are both unstable at both side surfaces of the patterned spacers 10. Accordingly, stability is low for external impact applied to the side surface of the patterned spacers 10. In particular, low stability is pronounced in liquid crystal display panel devices having ferroelectric liquid crystal cells, wherein portions of the upper and lower alignment layers 4 and 8 become uneven due to the physical deformation resulting from the external impact.
FIGS. 7A and 7B are diagrams representing an alignment state of ferroelectric liquid crystals of the liquid crystal display panel device of FIG. 1 according to the related art. In FIG. 7A, the liquid crystal display panel device has an even alignment along a rubbing direction, whereas if there is any physical deformation due to external impact, alignment of the ferroelectric liquid crystal molecules, as shown in FIG. 7B, becomes uneven.